This invention relates to a ring binder mechanism for retaining loose-leaf pages, and in particular it relates to an improved mechanism for reducing snapping motion of ring members as they close and for securely locking closed ring members together.
As is known in the art, a typical ring binder mechanism retains loose-leaf pages, such as hole-punched papers, in a file or notebook. It generally features multiple rings each including two half ring members capable of selectively opening to add or remove papers, or selectively closing to retain papers and allow them to move along the rings. The ring members mount on two adjacent hinge plates that join together about a pivot axis for pivoting movement within an elongated housing. The housing loosely holds the hinge plates so they may pivot relative to the housing. The undeformed housing is slightly narrower than the joined hinge plates when the hinge plates are in a coplanar position (180°). So as the hinge plates pivot through this position, they deform the resilient housing and cause a spring force in the housing, urging the hinge plates to pivot away from the coplanar position either opening or closing the ring members. Thus, when the ring members are closed, this spring force resists hinge plate movement and clamps the ring members together. Similarly, when the ring members are open, the spring force holds them apart. An operator may typically overcome this force by manually pulling the ring members apart or pushing them together. In addition, in some mechanisms the operator may move a lever located at one or both ends of the mechanism for moving the hinge plates through the coplanar position to open or close the ring members (in addition to manually pulling the ring members apart or pushing them together).
One drawback to these typical ring binder mechanisms is that when the ring members close, the housing's spring force snaps them together rapidly and with a force that might cause fingers to be pinched between the ring members. The substantial spring force required to keep the ring members closed also makes pivoting the hinge plates through the coplanar position difficult, making it hard to both open and close the ring members. Another drawback is that when the ring members are closed, they do not positively lock together. So if the mechanism accidentally drops, the ring members may unintentionally open. Still another drawback is that over time the housing may begin to permanently deform, reducing its ability to uniformly clamp the ring members together and possibly causing uneven movements or gaps between closed ring members.
To address these concerns, some ring binder mechanisms include a control slide directly attached to the lever. These control slides have inclined cam surfaces that project through openings in the hinge plates for rigidly controlling the hinge plates' pivoting motion both when opening and closing the ring members. Examples of these types of mechanisms are shown in U.S. Pat. Nos. 4,566,817, 4,571,108, and 6,276,862 and in U.K. Pat. No. 2,292,343. Some of these cam surfaces include a stop for blocking the hinge plates' pivoting motion when the ring members are closed, locking the closed ring members together.
But these mechanisms still have several drawbacks, including that when the ring members close the housing's spring force may still snap them together. The spring force may also still make both opening and closing the ring members difficult. Furthermore, the control slides in these mechanisms, specifically the inclined cam surfaces and stops, are complexly shaped and can be difficult and time consuming to fabricate. Also, since the control slides directly bias the hinge plates, they are usually relatively wide and may need to be constructed of a large gauge metal to withstand forces associated with repeated use (i.e., repeatedly biasing the hinge plates to pivot). Therefore, the openings in the hinge plates receiving these control slides may also be relatively wide, possibly weakening the hinge plates so that they too must be made of a large gauge metal. These uses of large gauge metal may make mass production more costly.
Other ring binder mechanisms attempt to address the issues of avoiding snapping motion of the ring members and positively locking the ring members in the closed position. For instance, some mechanisms arrange the hinge plates so that they never pass through the coplanar position in their pivoting motion. As a result of avoiding the coplanar position of the hinge plates, the ring members do not violently snap together upon closing. However, a closing force applied to the ring members is relatively weak so that it is necessary to provide a separate locking device to keep the ring members closed. One example of this type of ring mechanism is shown in U.S. Pat. No. 5,660,490. Still another solution is to arrange the hinge plates and housing so that the hinge plates are only weakly biased by the housing. This may be accomplished by adding a separate wire form spring to the underside of the hinge plates to provide a bias for pivoting the hinge plates to a position in which the ring members are open. An example of this ring binder mechanism construction is shown in U.S. Pat. Appl. Publ. No. 2003/0123923 to Koike, et al. In these types of mechanisms, the ends of the ring members are formed with hooks that are engaged upon closing to hold the ring members in the closed position. It requires some dexterity to manipulate the ring members to engage and disengage them. The manipulation becomes even more difficult if the ring members are filled with loose-leaf pages. Further, the hooks are more susceptible to forces that may unintentionally open the ring binder. Moreover, ring binder mechanisms having multiple ring members requiring simultaneous engagement or disengagement of hooks may make operation more awkward and difficult.
Consequently, there is a need for a ring binder mechanism that securely locks for retaining loose-leaf pages but has ring members that easily open and close as pages accumulate and do not snap together when the ring members close. The present invention is directed to such a ring binder mechanism.